Turbine assemblies include, without limitation, turbine sections of steam turbines and compressor and/or turbine sections of gas turbines. A steam turbine has a steam path which typically includes, in serial-flow relationship, a steam inlet, a turbine, and a steam outlet. A gas turbine has a gas path which typically includes, in serial-flow relationship, an air intake (or inlet), a compressor, a combustor, a turbine, and a gas outlet (or exhaust nozzle). Gas or steam leakage, either out of the gas or steam path or into the gas or steam path, from an area of higher pressure to an area of lower pressure, is generally undesirable. For example, gas-path leakage in the turbine or compressor area of a gas turbine, between the rotor of the turbine or compressor and the circumferentially surrounding turbine or compressor casing, will lower the efficiency of the gas turbine leading to increased fuel costs. Additionally, gas-path leakage in the combustor area of a gas turbine will require an increase in burn temperature to maintain power level, such increased burn temperature leading to increased pollution, such as increased NOx and CO production. Also, steam-path leakage in the turbine area of a steam turbine, between the rotor of the turbine and the circumferentially surrounding casing, will lower the efficiency of the steam turbine leading to increased fuel costs.
Seals are used to minimize leakage of fluids. A known fluid-path leakage seal is a cloth seal having a generally impervious and uniformly-thick shim assemblage and a cloth assemblage generally surrounding the shim assemblage. Cloth seals may be used in many applications including, but not limited to, seal assemblies for steam turbines and gas turbines used for power generation and seal assemblies for gas turbines used for aircraft and marine propulsion.
Another known fluid-path leakage seal is a manually-rigid metal seal for sealing the gap between two circumferentially-adjacent (and non-rotating) transition pieces of a power-system gas turbine. Such metal seal has a uniform thickness and has the general shape of an elongated rectangular metal bar. One elongated edge of the metal bar is engaged in a surface groove of one transition piece. The other elongated edge of the metal bar is engaged in a matching and aligned surface groove of the other transition piece. One end of the metal bar serves as a mounting bracket, typically having a mounting guide hole and a right-angle bend, which is used to secure the seal to a (non-rotating) first-stage nozzle. The grooves of transition pieces are not perfectly machined, and the grooves of transition pieces installed in power-system gas turbines are not perfectly aligned. Under actual field conditions during turbine maintenance downtime, it typically takes several days to replace all of such transition-piece metal seals in a standard power-system gas turbine. It is not unusual for such metal seals to break after only 100 to 4,000 hours of turbine operation. It is known that liberated pieces of broken metal seals have damaged other components of the turbine, such as rotating turbine blades downstream of the first-stage nozzle. Shutting down a power-system gas turbine to replace a broken seal is a costly undertaking in terms of lost electrical-generating capacity.